The present invention relates to an electric power tool.
In the following, the term “electric power tool” includes wall saws and drilling equipment that have diamond tools equipped with cutting segments in the form of saw blades or drill bits; in addition to diamond tools, tools with cutting materials that function in a similar manner may also be used. Wall saws are used to cut through reinforced and un-reinforced walls, ceilings and floors made of concrete or similar substrates and are used in building construction and civil engineering for redevelopment and renovations. It may be necessary in demolition or remodeling work to cut through or tear down already existing concrete walls or cut out areas of the concrete walls. Drilling equipment is used to create boreholes in concrete, brick, masonry and other mineral substrates.
In the case of abrasive machining with diamond tools, it is necessary to cool the diamond tool in the region of the machining location in order to avoid damage to the diamond tool due to overheating. The cutting segments of the diamond tools are cooled during the machining process by means of a cooling fluid in order to support the machining process and increase the service life of the cutting segments. Because of the high power outputs of the cited electric power tools, the motor and the power electronics must also be cooled with a cooling medium along with the diamond tool. To guarantee the required cooling rates, air cooling of the motors and power electronics would produce power tools that are very large and heavy.
An electric power tool comprises a tool, which is designed to be rotatable around a rotational axis, a motor assembly having at least one motor which rotates the tool around the rotational axis, a motor housing having at least one receiving area for the motor, a cooling element for cooling the at least one motor and an electronic assembly having at least one electronic component to be cooled.
An electric wall saw known as the TS-5 comprises a motor housing for the motor assembly and an electronic housing for the electronic assembly. The to-be-cooled electronic components of the electronic assembly are mounted on a cooling element designed as a cooling plate. The cooling plate has a cooling structure with one or more cooling channels, through which a cooling medium flows for cooling. The cooling of the motor occurs via a cooling channel, which surrounds the motor in a spiral-shaped manner. The cooling medium flows into the electronic housing via an inlet port, flows through the cooling plate of the electronic cooling, then through the spiral-shaped cooling channel of the motor cooling and from there via a cooling borehole into the saw arm. The cooling medium flows via outlet openings in the saw blade flange and cools the saw blade during processing.
In the case of an electric wall saw known as the TS-20, the electronic assembly is not in the saw head, but housed in a separate supply unit. Like the TS-5, the electronic components of the electronic assembly are mounted on a cooling plate, which has a cooling structure with cooling channels. The saw head is connected to the supply unit via a line. The cooling circuit comprises the electronic cooling, the motor cooling and the saw blade cooling.
The disadvantage is that a cooling plate with cooling channels is required to cool the electronic assembly. In addition, the cooling medium flows through the electronic assembly, which increases the risk of a short circuit from moisture.
The object of the present invention is simplifying the cooling of the electronic assembly and reducing the number of structural elements required for the electronic cooling. Furthermore, the risk of a short circuit during cooling of the electronic assembly is reduced.
According to the invention, it is provided that the cooling of the at least one to-be-cooled electronic component of the electronic assembly is carried out via the motor housing. The number of sealing locations is reduced by integrating the cooling surfaces and/or cooling boreholes into the motor housing. As a result, the danger of the electronic components coming into contact with the cooling medium is reduced.
A cooling surface for an electronic component to be cooled is preferably provided on the motor housing. It is advantageous that the size of the cooling surface may be adapted to the electronic component to be cooled. As a result, the available construction space of the motor housing may be used in the best possible manner and the power tool may be designed to be smaller and lighter.
In a preferred embodiment, at least one cooling borehole for an electronic component to be cooled is provided in the motor housing. The advantage of the cooling borehole is that cylindrical electronic components such as, for example, braking resistors, may be cooled via the surrounding housing surfaces of the motor housing. The construction space of the motor housing is utilized and the power tool may be designed to be smaller and lighter.
It is especially preferred that at least one cooling surface is provided on the motor housing and/or at least one cooling borehole is provided in the motor housing for each to-be-cooled electronic component of the electronic assembly. The number of sealing locations is reduced because the cooling medium flows through only the cooling element. This reduction lowers the risk of the electronic components coming into contact with the cooling medium and the cooling medium causing damage to the electronic components.
Exemplary embodiments of the invention are described in the following on the basis of the drawings. These drawings are not necessarily supposed to represent the exemplary embodiments to scale, rather the drawings are executed in a schematic and/or slightly distorted form when it is useful for explanatory purposes. Reference is made to the pertinent prior art with respect to additions to the teachings directly identifiable from the drawings. It must be taken into consideration in this case that a wide range of modifications and changes related to the form and detail of an embodiment may be undertaken without deviating from the general idea of the invention. The features of the invention disclosed in the description, the drawings as well as in the claims may be essential for the further development of the invention both separately as well as in any combination. Moreover, all combinations of at least two features disclosed in the description, the drawings and/or the claims fall within the scope of the invention. The general idea of the invention is not restricted to the exact form or detail of the preferred embodiment described and depicted in the following or restricted to a subject matter which would be limited as compared to the subject matter claimed in the claims. In the case of any dimensioning ranges given, values within the stated limits are also meant to be disclosed as limit values, and be applicable at will and claimable. For the sake of simplicity, the same reference numbers are used in the following for identical or similar parts having an identical or similar function.